1. Field
The present disclosure relates generally to rendering technology and, more specifically, to importance sampling for hair scattering.
2. Related Art
Media productions have used increasingly complex algorithms in order to create more realistic images. Increased emphasis has been directed towards the display and animation of hair, reflecting the ubiquitous nature of hair as an element of human and animal characters.
While it is important to providing characters with a realistic appearance, high-quality hair rendering has been a particularly challenging feature. Early works employed hair modeled by computing light scattering using thin cylinders. See Kajiya, J. T., and Kay, T. L., Rendering Fur with Three Dimensional Textures, Computer Graphics (Proceedings of SIGGRAPH 89), pp. 271-280 (1989). Later works improved upon this model by incorporating internal path analysis of hair strands. See Marschner et al., Light Scattering from Human Hair Fibers, ACM Transactions on Graphics Vol 22, Issue 3, pp. 780-791 (July 2003). While models focusing on providing a bidirectional scattering distribution function (bsdf) for hair have been proposed, none provide an efficient method to importance sample the scattering function.